The present invention relates to superalkalinized alkylaryl sulfonates of alkaline earth metals obtained from linear alkylaryl sulfonic acids, and useful as detergent/dispersant additives for lubricating oils, processes for their preparation and an intermediate alkylation product.
It is already known in the prior art to prepare slightly or highly superalkalinized sulfonates from sulfonic acids obtained by the sulfonation of different alkylaryl hydrocarbons and of an excess of alkaline earth base.
The alkylaryl hydrocarbons subjected to the sulfonation reaction result from alkylation by the Friedel-Crafts reaction of different aryl hydrocarbons, particularly aromatic, by two different types of olefin:
branched olefins resulting from the oligo-polymerization of propylene to C15 to C40 hydrocarbons, particularly the tetra polymer of propylene dimerized into a C24 olefin, and
linear olefins that result from the oligo-polymerization of ethylene to C14 to C40 hydrocarbons.
Thus European Patent No. 1.318 to the company Exxon, published in 1981, describes superalkalinized mono alkyl orthoxylene sulfonates and mono alkyl toluene sulfonates resulting from the alkylation of the corresponding aromatic hydrocarbons by a mixture of branched olefins comprising a maximum proportion of 30% of linear olefin.
Furthermore, French Patent No. 2.564.830 to the company Orogil, the former name of the Assignee, and whose corresponding application was published in 1985, and which corresponds to U.S. Pat. No. 4,764,295 describes alkylaryl sulfonates of alkaline earth metals resulting from alkylation by a linear olefin.
In both cases, the alkylation reaction takes place in the presence of a Friedel-Crafts catalyst with a high excess of moles of the aryl hydrocarbon with respect to those of the olefin, to obtain, after recycling said excess, the corresponding mono alkylaryl hydrocarbon.
The present invention has for subject matter a superalkalinized alkyaryl sulfonate of alkaline earth metal, wherein the aryl radical is other than phenol, the alkyl chain is a linear chain that contains between 14 and 40 carbon atoms, and the aryl sulfonate radical of alkaline earth metal is fixed, in a molar proportion comprised between 0 and 13% in positions 1 or 2 of the linear alkyl chain.
Preferably, the aryl sulfonate radical of alkaline earth metal is fixed, in a molar proportion comprised between 5 and 11% in positions 1 or 2 of the linear alkyl chain, more preferably, between 7 and 10% in positions 1 or 2 of the linear alkyl chain.
Preferably, the aryl radical is either a tolyl, xylyl, o xylyl, ethyl phenyl, or cumenyl radical.
Preferably, the alkyl chain contains between 16 and 30 carbon atoms, more preferably, between 20 and 24 carbon atoms.
The present invention also has for subject matter a new intermediate compound, an alkylaryl hydrocarbon comprising a nonphenyl aryl substituent on a linear alkyl chain containing between 14 and 40 carbon atoms, wherein the molar proportion of aryl substituent on positions 1 and 2 of the linear alkyl chain is comprised between 0 and 13%.
Preferably, the molar proportion of aryl substituent on positions 1 and 2 of the linear alkyl chain is comprised between 5 and 11%, more preferably, between 7 and 10%.
Preferably, the aryl radical is either a tolyl, xylyl, o xylyl, ethyl phenyl, or cumenyl radical.
Preferably, the alkyl chain contains between 16 and 30 carbon atoms, more preferably, between 20 and 24 carbon atoms.
The present invention also has for subject matter a process for the preparation of the alkylaryl hydrocarbon comprising the steps of:
(a) the isomerization of a linear mono-alpha olefin containing between 14 and 40 carbon atoms to produce a linear mono-olefin containing a molar proportion of between 0 and 13% of alpha olefin,
(b) the alkylation, by the Friedel-Crafts reaction, of an aryl hydrocarbon other than benzene by the linear mono-olefin.
Preferably, the linear mono-olefin contains a molar proportion of between 5 and 11% of alpha olefin, more preferably, between 7 and 10% of alpha olefin,
The present invention also has for subject matter a second process for the preparation of the alkylaryl hydrocarbon comprising the alkylation, by the Friedel-Crafts reaction, of an aryl hydrocarbon other than benzene by a linear mono-olefin containing between 14 and 40 carbon atoms, and having a molar proportion of alpha olefin of at least 80%, wherein the alkylation takes place in a first step in which the molar ratio between the aryl hydrocarbon and the linear mono-alpha olefin is a maximum of 1.5, and in a second step in which said ratio is a minimum of 2. Preferably, the alkylation takes place in a first step in which the molar ratio between the aryl hydrocarbon and the linear mono-alpha olefin is a maximum of 1, and in a second step in which said ratio is a minimum of 5.
The superalkalinized alkylaryl sulfonate of alkaline earth metal can be produced by the sulfonation of the alkylaryl hydrocarbon intermediate produced by either process, and the reaction of the resulting sulfonic acid with an excess of alkaline earth base. The catalyst used in the Friedel-Crafts reaction can be hydrofluoric acid, aluminum chloride, boron fluoride, a sulfonic ion exchange resin, or an acid activated clay.